1. Field of the Invention
The present invention relates to a transfer control system and transfer control method, and in particular, to a transfer control system and transfer control method for controlling transfer of a call in a communication system.
2. Description of the Prior Art
Generally, a call transmitted between two communication terminals can be transferred to a third party. That is, as shown in FIG. 11, in a state where communication terminals 1 and 2 communicate with each other via a communication control devices A, E, and B, a call can be transferred to a third party, specifically a communication terminal 3, thereby realizing a state change from the above state to another state where the communication terminals 3 and 2 communicate with each other via the communication control devices C, E, and B. In order to carry out such a transfer, first, the communication terminal 1 sends out a transfer command S101. Then, a transfer shown by an arrow S102 is carried out under the control of the communication control device A, and the state represented by broken lines in the drawing is changed into another state represented by thick solid lines in the same drawing. In this way, a call can be transferred.
In addition, from the destination third party (communication terminal 3 in FIG. 11), a call can be further transferred to another third party (for example, a communication terminal 4, not shown) in the same way. However, the source communication terminal (communication terminal 1 in FIG. 11) cannot issue a transfer command for the call.
Furthermore, a destination can be specified only by a user manually entering or selecting among from a destination list previously registered.
In the above-described system, once a communication terminal transfers a call involved in communication to a third party, the terminal cannot perform an action on the call such as command for transferring the call. Since the terminal cannot perform such an action, it cannot transfer again the call to another third party or itself.
Furthermore, in the above-described system, a destination can be specified only by entering the telephone number of the destination or selecting the telephone number stored in the communication terminal. Therefore, a user must push buttons over and over, resulting in the user convenience being degraded.
The present invention is devised to solve the problems of the prior art described above, and an object of the present invention is to provide a transfer control system and transfer control method that allow a call to be retransferred by a command from the source communication terminal and are capable of improving the convenience of a user issuing the command.
A transfer control system according to the present invention includes storage means for storing in-communication information describing that a second terminal and a third terminal are now in communication with each other after a call is transferred in a state where a first terminal and the second terminal are in communication with each other; and call transfer means for transferring the call to a fourth terminal by referring to the in-communication information stored in the storage means when a transfer command is issued by the first terminal, thereby establishing communication between the second and fourth terminals.
Here, the first and fourth terminals may be different from each other, or may be identical with each other. In the former case, the transfer control system further includes means for making address inquiry via a rectilinear propagation channel, that is provided on the first terminal, and means, that is provided on another terminal, for sending back the address of the terminal itself to the first terminal in response to the address inquiry from the first terminal, in which the first terminal uses the received address to issue the transfer command.
A transfer control method according to the present invention includes a storing step of storing in-communication information describing that a second terminal and a third terminal are now in communication with each other after a call is transferred in a state where a first terminal and the second terminal are in communication with each other, and a call transfer step of transferring the call to a fourth terminal by referring to the in-communication information stored in the storing step when a transfer command is issued by the first terminal, thereby establishing communication between the second and fourth terminals.
Here, the first and fourth terminals may be different from each other, or may be identical with each other. In the former case, the transfer control method further includes an inquiry step of making address inquiry from the first terminal to another terminal via a rectilinear propagation channel, and a send-back step of sending back, in another terminal, the address of the terminal itself to the first terminal in response to the address inquiry from the first terminal, in which, in the call transfer step, the first terminal uses the address received in the send-back step to issue the transfer command.
A transfer control terminal according to the present invention using storage device for storing in-communication information describing terminals that are now in communication after a call is transferred includes means for making address inquiry to another terminal; and means for issuing command for re-transferring the cal to the storage device using received addressed from the another terminal.
Here, the address inquiry is carried out via rectilinear propagation channel. In one embodiment he command for re-transferring the call, a terminal that now in communication before transfer the call and said another terminal are different from each other. In another embodiment the command for re-transferring the call, a terminal that now in communication before transfer the call and said another terminal are identical with each other.
In short, according to the present invention, after a call being transmitted is transferred to a third party, the call can be further transferred to another third party by a command from the source communication terminal.
Alternatively, after a call being transmitted is transferred to a third party, the call can be further transferred to the source communication terminal by a command from the source communication terminal.
The destination address maybe automatically set through communication between the terminals or may be manually set without such a communication. The destination address may be the address of the source terminal itself.